Potentiometer

ABSTRACT

A potentiometer comprising a housing having an elongated leadscrew rotatably mounted therein. A wiper block is mounted on the leadscrew and adapted for longitudinal movement thereon when the leadscrew is rotated. A resistance element is mounted in the housing adjacent the leadscrew. A collector bar is also positioned in the housing and is spaced from and extending above the resistance element, and is disposed in a plane parallel to the leadscrew. A wiper means is secured to the block means and has a plurality of juxtapositioned fingers adapted to engage the resistance element. A collector arm is connected to the wiper means and slidably engages the collector bar.

United States Patent [191 King et al. 1 Aug. 13, 1974 1 5 4 1 POTENTIOMETER [75] Inventors: Robert F. Klug; Larry B. Lindquist, Prlma'y Emmmer' j' Truhe both of Columbus, Nebr.

[73] Assignee: Dale Electronics Inc., Columbus,

Nebr.

[22] Filed: Apr. 26, 1973 [21] Appl. No.: 354,482

[52] US. Cl. 338/180, 338/183 [51] Int. Cl ..H01c 9/02 [58] Field of Search 338/180, 183, 176, 202

A [56] References Cited UNITED STATES PATENTS 2,926,324 2/1960 Barden et a1. 338/180 3,497,858 2/1970 Norris 338/183 3,634,805 1/1972 .lestrzemski et a1 338/180 3,703,699 11/1972 Lahm et a] 338/180 3,704,436 11/1972 Froebe et a1 338/180 3,733,573 5/1973 Dieterich 338/202 Assistant Examiner-David A. Tone Attorney, Agent, or FirmZarley, McKee, Thomte & Voorhees 5 7 ABSTRACT A potentiometer comprising a housing having an elongated leadscrew rotatably mounted therein. A wiper block is mounted on the leadscrew and adapted for longitudinal movement thereon when the leadscrew is rotated. A resistance element is mounted in the housing adjacent the leadscrew. A collector bar is also p0- sitioned in the housing and is spaced from and extending above the resistance element, and is disposed in a plane parallel to the leadscrew. A wiper means is secured to the block means and has a plurality of juxtapositioned fingers adapted to engage the resistance element. A collector arm is connected to the wiper means and slidably engages the collector bar.

11 Claims, 5 Drawing Figures POTENTl-OMETER BACKGROUND OF TI-IE INVENTION This invention relates to a potentiometer and more particularly to a potentiometer wherein all of the finger elements of the wiper engage the resistance element to achieve improved efficiency.

Conventional potentiometers generally comprise a wiper means which not only engages the resistance element but which also engages the collector means or bar. The efficiency of the potentiometer is reduced if a portion of the wiping fingers are in engagement with the collector bar. Further, the conventional potentiometers do experience some electrical noise due to the limited contact area between the wiper and the resistance element.

Therefore, it is a principal object of the invention to provide an improved potentiometer.

A further object of the invention is to provide a potentiometer having a wiper element including a plurality of wiper fingers, all of which are in engagement with the resistance element.

A further object of the invention is to provide a potentiometer having improved efficiency.

A further object of the invention is to provide a potentiometer which experiences less electrical noise than conventional potentiometers.

A further object of the invention is to provide a metal-to-metal contact between the wiper fingers and the collector bar.

A further object of the invention is to provide a potentiometer having improved resolution.

A further object of the invention is to provide a po tentiometer which is economical of manufacture and durable in use.

These and other objects will be apparent to those skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS This invention consists in the construction, arrangements and combination of the various parts of the device, whereby the objects contemplated are attained as hereinafter more fully set forth, specifically pointed out in the claims, and illustrated in the accompanying drawings, in which:

FIG. 1 is a longitudinal sectional view of the potentiometer:

FIG. 2 is a sectional view seen on lines 2 2 of FIG. 1:

FIG. 3 is an enlarged sectional view seen on lines 3 3 of FIG; 1:

FIG. 4 is a sectional view seen on lines 4 4 of FIG. 3; and

FIG. 5 is an exploded perspective view of the wiper block and wiper element.

DESCRIPTION OF THE PREFERRED EMBODIMENT The potentiometer of this invention is referred to generally by the reference numeral and comprising a housing 12 including an upper housing element 14 and a lower layer of epoxy 16.

Upper housing element 14 includes a top 18, sides and 22, ends 24 and 26, and an open bottom 28 defined by annular shoulder 30. The ceramic layer 80 is adapted to engage the annular shoulder 30 to achieve the connection between the two 'housi'ng members with the housing being sealed in-eonventional fashion.

A leadscrew 32 is rotatably mounted in upper housing member 14 as iIIustrat-edin the drawings. The numeral 34 refers to a wiper block which is mounted on the leadscrew 32 for longitudinal-movement on the leadscrew 32 upon rotation thereof.

Wiper block 34 includes a longitudinal arcuate channel 36 at its upper end which receives the leadscrew 32. An elongated channel 38 is formed in the bottom of the wiper block 34 and has a cylindrical boss 40 extending downwardly therein. Side wall 42 of wiper block 34 is provided with a downwardly extending guide arm 44. The numeral 46 refers to a notch formed in side wall 48 of wiper block 34. A pair of guide arms 50 and 52 extend downwardly from side wall 48 on opposite sides of the notch 46 as illustrated in FIG. 5.

The numeral 54 refers to a support which is secured to the wiper block 34 as illustrated in the drawings. Support 54 has an opening 56 formed in its end portion 58 which is adapted to frictionally embrace the boss 40. End portion 58 is received in the channel 38 as illustrated in FIG. 3. Collector arm 60 extends upwardly from end portion 58 and is received by the notch 46 as seen in the drawings. Collector arm 60 is provided with an arcuate portion 62 which is adapted to wipe upon the collector 64 positioned at the inside surface of wall 22 of housing element 14. A terminal prong 66 extends downwardly from the collector 64 through the lower housing member 16 as seen in FIG. 3.

The numeral 68 refers to a wiper element secured to the end portion 70 of support 54. Wiper 68 comprises a plurality of juxtapositioned fingers 72 having a plate 74 securing their upper ends together as seen in the drawings. Plate 74 is secured to end portion 70 of support 54 by any conventional means. The fingers 72 are bent to define an arcuate wiping surface 76 which is adapted to slidably engage the upper surface of an elongated resistance means 78 which is positioned on the ceramic sheet 80 which is secured by the layer of epoxy 16. Preferably, resistance means 78 is of the film type deposited on the ceramic member 80 by any conventional means. A pair of terminal prongs 82 and 84 are electrically connected to the opposite ends of the resistance means 78 and extend downwardly through the epoxy layer 16 as illustrated in the drawings.

The method of assembling the potentiometer is as follows. The leadscrew 32 is rotatably journaled in the housing member 14 in conventional fashion. The support 54 is snapped onto the wiper block 32 so that the wiper fingers 72 are positioned therebelow as previously described. The wiper block 34 is then mounted on the leadscrew 32 so that the channel 36 receives the leadscrew as also previously described. Ordinarily, the collector 64 would have been previously mounted in the upper housing member 14. The upper housing member 14 is then placed on the layer of epoxy l6 and ceramic 80 so that the wiping portion 76 of all of the wiper fingers 72 slidably engages the upper surface of the resistance means 78. The arcuate portion 62 of the collector arm 60 engages the collector 64 as illustrated in the drawings. The guide arms 44, 50 and 52 are closely positioned adjacent the upper surface of the ceramic member 80 to prevent undesirable tipping or tilting of the wiper block 34 with respect to the housing.

It can be seen that the collector 64 is disposed in a plane remote from but parallel to the planeof the resistance means 78. All of the wiper fingers 72 engage the resistance means 78 to provide improved potentiometer efficiency. Less electrical noise is experienced in the instant potentiometer when compared to the prior art potentiometers by reason of the greater contact area between the wiper fingers and the resistance element. The metal-to-metal contact between the wiper fingers and the collector also lowers contact resistance and electrical noise.

Rotation of the leadscrew 32 causes longitudinal movement of the wiper block 34 so that the wiper fingers 72 are moved with respect to the resistance means 78 to change the resistance of the potentiometer. Thus it can be seen that a unique potentiometer has been provided which is simple of construction but which achieves vastly superior efficiency when compared to the potentiometers of the prior art. It can therefore be seen that the potentiometer accomplishes at least all of its stated objectives.

We claim:

1. A potentiometer comprising a housing,

an elongated leadscrew rotatably mounted in said housing;

block means having upper and lower ends on said leadscrew adapted for longitudinal movement on said leadscrew when said leadscrew is rotated,

elongated resistance means in said housing disposed adjacent said leadscrew,

a collector bar in said housing spaced from and extending above said resistance element and being disposed in a plane parallel to said leadscrew;

a support means mounted to said block means adjacent said lower end thereof, said support means having a collector arm and a wiper means thereon, said collector arm and said wiper means being electrically interconnected,

said wiper means having a plurality of juxtapositioned fingers engaging said resistance means for sliding movement therealong,

said collector arm extending upwardly adjacent one side of said block means for sliding engagement with said collector bar.

2. The potentiometer of claiml wherein said resistance means comprises a flat, substantially rectangular resistance element, each of said fingers having a wiping portion which yieldably and slidably engages said resistance element.

3. A potentiometer according to claim 2 wherein said block means is secured to said leadscrew at its upper end, said block means having a channel formed in its lower end, said support means being mounted in said channel, said fingers being secured to said support means.

4. The potentiometer of claim 3 wherein said collector arm is integrally formed with said support means.

5. The potentiometer of claim 4 wherein said support means comprises first and second ends, said first end of said support means being detachably secured to said block means, said second end of said support means being disposed in an inclined plane with respect to said first end, said fingers being secured at one end thereof to said second end of said support means.

6. The potentiometer of claim 5 wherein said support means is resilient to permit said second end to deflect with respect to said first end.

7. The potentiometer of claim 6 wherein said fingers are comprised of a resilient material.

8. The potentiometer of claim 1 wherein said block means has a vertically disposed channel formed in one side thereof, said collector arm being at least partially positioned in said vertically disposed channel.

9. The potentiometer of claim 1 wherein said block means has an arcuate channel formed in its upper end, said arcuate channel detachably receiving said leadscrew.

10. A potentiometer comprising:

a housing,

an elongated leadscrew rotatably mounted in said housing,

a block means on said leadscrew and having upper and lower ends, said block means being adapted for longitudinal movement on said leadscrew when said leadscrew is rotated,

a resistance means in said housing disposed adjacent said leadscrew;

a collector bar in said housing positioned above said resistance element,

a wiper means attached to said block means, said wiper means having a plurality of juxtapositioned fingers adapted to engage said resistance means,

a collector arm connected to said wiper means and engaging said collector bar,

a resistance support positioned below said resistance element,

said block means having a channel formed in its lower end;

an electrically conductive support means mounted in said channel, said fingers being secured to said support means,

said block means having guide arms extending downwardly therefrom on opposite sides of said resistance element.

11. The potentiometer of claim 10 wherein said resistance element support comprises a flat ceramic member, said resistance element being film deposited on said ceramic member. 

1. A potentiometer comprising a housing, an elongated leadscrew rotatably mounted in said housing; block means having upper and lower ends on said leadscrew adapted for longitudinal movement on said leadscrew when said leadscrew is rotated, elongated resistance means in said housing disposed adjacent said leadscrew, a collector bar in said housing spaced from and extending above said resistance element and being disposed in a plane parallel to said leadscrew; a support means mounted to said block means adjacent said lower end thereof, said support means having a collector arm and a wiper means thereon, said collector arm and said wiper means being electrically interconnected, said wiper means having a plurality of juxtapositioned fingers engaging said resistance means for sliding movement therealong, said collector arm extending upwardly adjacent one side of said block means for sliding engagement with said collector bar.
 2. The potentiometer of claim 1 wherein said resistance means comprises a flat, substantially rectangular resistance element, each of said fingers having a wiping portion which yieldably and slidably engages said resistance element.
 3. A potentiometer according to claim 2 wherein said block means is secured to said leadscrew at its upper end, said block means having a channel formed in its lower end, said support means being mounted in said channel, said fingers being secured to said support means.
 4. The potentiometer of claim 3 wherein said collector arm is integrally formed with said support means.
 5. The potentiometer of claim 4 wherein said support means comprises first and second ends, said first end of said support means being detachably secured to said block means, said second end of said support means being disposed in an inclined plane with respect to said first end, said fingers being secured at one end thereof to said second end of said support means.
 6. The potentiometer of claim 5 wherein said support means is resilient to permit said second end to deflect with respect to said first end.
 7. The potentiometer of claim 6 wherein said fingers are comprised of a resilient material.
 8. The potentiometer of claim 1 wherein said block means has a vertically disposed channel formed in one side thereof, said collector arm being at least partially positioned in said vertically disposed channel.
 9. The potentiometer of claim 1 wherein said block means has an arcuate channel formed in its upper end, said arcuate channel detachably receiving said leadscrew.
 10. A potentiometer comprising: a housing, an elongated leadscrew rotatably mounted in said housing, a block means on said leadscrew and having upper and lower ends, said block means being adapted for longitudinal movement on said leadscrew when said leadscrew is rotated, a resistance means in said housing disposed adjacent said leadscrew; a collector bar in said housing positioned above said resistance element, a wiper means attached to said block means, said wiper means having a plurality of juxtapositioned fingers adapted to engage said resistance means, a collector arm connected to said wiper means and engaging said collector bar, a resistance support positioned below said resistance element, said block means having a channel formed in its lower end; an electrically conductiVe support means mounted in said channel, said fingers being secured to said support means, said block means having guide arms extending downwardly therefrom on opposite sides of said resistance element.
 11. The potentiometer of claim 10 wherein said resistance element support comprises a flat ceramic member, said resistance element being film deposited on said ceramic member. 